with open(file='main.log', mode='r') as fopen:
    for line in fopen:
        print(line, end='')
# 2021-03-05 17:16:34,829 - set.py[line:4] - this is error message1
# 2021-03-05 17:16:34,831 - set.py[line:5] - this is error message2